Can't be decompiled - Cannot invoke String.isEmpty()

[aoqia194]

Vineflower version

1.10.1

Describe the bug

The decompiler failed to decompile some things. I do not have the rights to distribute the original .java file, so I am sorry for the abstraction of details in this report. Even though this is the case, I am still posting this to be of some help.

Additional information

// $VF: Couldn't be decompiled
// Please report this to the Vineflower issue tracker, at https://github.com/Vineflower/vineflower/issues with a copy of the class file (if you have the rights to distribute it!)
// java.lang.RuntimeException: java.lang.NullPointerException: Cannot invoke "String.isEmpty()" because "keyField" is null
//   at org.jetbrains.java.decompiler.main.ClassesProcessor.processClass(ClassesProcessor.java:439)
//   at org.jetbrains.java.decompiler.main.Fernflower.processClass(Fernflower.java:183)
//   at org.jetbrains.java.decompiler.struct.ContextUnit.lambda$save$2(ContextUnit.java:164)
// Caused by: java.lang.NullPointerException: Cannot invoke "String.isEmpty()" because "keyField" is null
//   at org.jetbrains.java.decompiler.main.rels.NestedClassProcessor.getMaskLocalVars(NestedClassProcessor.java:747)
//   at org.jetbrains.java.decompiler.main.rels.NestedClassProcessor.computeLocalVarsAndDefinitions(NestedClassProcessor.java:338)
//   at org.jetbrains.java.decompiler.main.rels.NestedClassProcessor.processClass(NestedClassProcessor.java:67)
//   at org.jetbrains.java.decompiler.main.ClassesProcessor.processClass(ClassesProcessor.java:431)
//   at org.jetbrains.java.decompiler.main.Fernflower.processClass(Fernflower.java:183)
//   at org.jetbrains.java.decompiler.struct.ContextUnit.lambda$save$2(ContextUnit.java:164)

// $VF: Couldn't be decompiled
      // Please report this to the Vineflower issue tracker, at https://github.com/Vineflower/vineflower/issues with a copy of the class file (if you have the rights to distribute it!)
      // java.lang.IllegalStateException: No successor exists for {If}:36
      //   at org.jetbrains.java.decompiler.modules.decompiler.stats.Statement.getFirstSuccessor(Statement.java:834)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfNode.build(IfNode.java:90)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeIfs(IfHelper.java:75)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:38)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfsRec(IfHelper.java:35)
      //   at org.jetbrains.java.decompiler.modules.decompiler.IfHelper.mergeAllIfs(IfHelper.java:20)
      //   at org.jetbrains.java.decompiler.main.rels.MethodProcessor.codeToJava(MethodProcessor.java:280)
      //
      // Bytecode:
      // 000: bipush 50
      // 002: anewarray 50
      // 005: astore 6
      // 007: bipush 0
      // 008: istore 7
      // 00a: iload 7
      // 00c: aload 6
      // 00e: arraylength
      // 00f: if_icmpge 024
      // 012: aload 6
      // 014: iload 7
      // 016: new org/lwjglx/util/glu/tessellation/PriorityQSort$Stack
      // 019: dup
      // 01a: invokespecial org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.<init> ()V
      // 01d: aastore
      // 01e: iinc 7 1
      // 021: goto 00a
      // 024: bipush 0
      // 025: istore 7
      // 027: ldc 2016473283
      // 029: istore 8
      // 02b: aload 0
      // 02c: aload 0
      // 02d: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.size I
      // 030: bipush 1
      // 031: iadd
      // 032: newarray 10
      // 034: putfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 037: bipush 0
      // 038: istore 1
      // 039: aload 0
      // 03a: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.size I
      // 03d: bipush 1
      // 03e: isub
      // 03f: istore 2
      // 040: bipush 0
      // 041: istore 5
      // 043: iload 1
      // 044: istore 3
      // 045: iload 3
      // 046: iload 2
      // 047: if_icmpgt 05b
      // 04a: aload 0
      // 04b: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 04e: iload 3
      // 04f: iload 5
      // 051: iastore
      // 052: iinc 5 1
      // 055: iinc 3 1
      // 058: goto 045
      // 05b: aload 6
      // 05d: iload 7
      // 05f: aaload
      // 060: iload 1
      // 061: putfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.p I
      // 064: aload 6
      // 066: iload 7
      // 068: aaload
      // 069: iload 2
      // 06a: putfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.r I
      // 06d: iinc 7 1
      // 070: iinc 7 -1
      // 073: iload 7
      // 075: iflt 1cd
      // 078: aload 6
      // 07a: iload 7
      // 07c: aaload
      // 07d: getfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.p I
      // 080: istore 1
      // 081: aload 6
      // 083: iload 7
      // 085: aaload
      // 086: getfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.r I
      // 089: istore 2
      // 08a: iload 2
      // 08b: iload 1
      // 08c: bipush 10
      // 08e: iadd
      // 08f: if_icmple 16f
      // 092: iload 8
      // 094: ldc 1539415821
      // 096: imul
      // 097: bipush 1
      // 098: iadd
      // 099: invokestatic java/lang/Math.abs (I)I
      // 09c: istore 8
      // 09e: iload 1
      // 09f: iload 8
      // 0a1: iload 2
      // 0a2: iload 1
      // 0a3: isub
      // 0a4: bipush 1
      // 0a5: iadd
      // 0a6: irem
      // 0a7: iadd
      // 0a8: istore 3
      // 0a9: aload 0
      // 0aa: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 0ad: iload 3
      // 0ae: iaload
      // 0af: istore 5
      // 0b1: aload 0
      // 0b2: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 0b5: iload 3
      // 0b6: aload 0
      // 0b7: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 0ba: iload 1
      // 0bb: iaload
      // 0bc: iastore
      // 0bd: aload 0
      // 0be: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 0c1: iload 1
      // 0c2: iload 5
      // 0c4: iastore
      // 0c5: iload 1
      // 0c6: bipush 1
      // 0c7: isub
      // 0c8: istore 3
      // 0c9: iload 2
      // 0ca: bipush 1
      // 0cb: iadd
      // 0cc: istore 4
      // 0ce: iinc 3 1
      // 0d1: aload 0
      // 0d2: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.leq Lorg/lwjglx/util/glu/tessellation/PriorityQ$Leq;
      // 0d5: aload 0
      // 0d6: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.keys [Ljava/lang/Object;
      // 0d9: aload 0
      // 0da: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 0dd: iload 3
      // 0de: iaload
      // 0df: aaload
      // 0e0: aload 0
      // 0e1: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.keys [Ljava/lang/Object;
      // 0e4: iload 5
      // 0e6: aaload
      // 0e7: invokestatic org/lwjglx/util/glu/tessellation/PriorityQSort.GT (Lorg/lwjglx/util/glu/tessellation/PriorityQ$Leq;Ljava/lang/Object;Ljava/lang/Object;)Z
      // 0ea: ifne 0ce
      // 0ed: iinc 4 -1
      // 0f0: aload 0
      // 0f1: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.leq Lorg/lwjglx/util/glu/tessellation/PriorityQ$Leq;
      // 0f4: aload 0
      // 0f5: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.keys [Ljava/lang/Object;
      // 0f8: aload 0
      // 0f9: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 0fc: iload 4
      // 0fe: iaload
      // 0ff: aaload
      // 100: aload 0
      // 101: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.keys [Ljava/lang/Object;
      // 104: iload 5
      // 106: aaload
      // 107: invokestatic org/lwjglx/util/glu/tessellation/PriorityQSort.LT (Lorg/lwjglx/util/glu/tessellation/PriorityQ$Leq;Ljava/lang/Object;Ljava/lang/Object;)Z
      // 10a: ifne 0ed
      // 10d: aload 0
      // 10e: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 111: iload 3
      // 112: iload 4
      // 114: invokestatic org/lwjglx/util/glu/tessellation/PriorityQSort.Swap ([III)V
      // 117: iload 3
      // 118: iload 4
      // 11a: if_icmplt 0ce
      // 11d: aload 0
      // 11e: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 121: iload 3
      // 122: iload 4
      // 124: invokestatic org/lwjglx/util/glu/tessellation/PriorityQSort.Swap ([III)V
      // 127: iload 3
      // 128: iload 1
      // 129: isub
      // 12a: iload 2
      // 12b: iload 4
      // 12d: isub
      // 12e: if_icmpge 150
      // 131: aload 6
      // 133: iload 7
      // 135: aaload
      // 136: iload 4
      // 138: bipush 1
      // 139: iadd
      // 13a: putfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.p I
      // 13d: aload 6
      // 13f: iload 7
      // 141: aaload
      // 142: iload 2
      // 143: putfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.r I
      // 146: iinc 7 1
      // 149: iload 3
      // 14a: bipush 1
      // 14b: isub
      // 14c: istore 2
      // 14d: goto 08a
      // 150: aload 6
      // 152: iload 7
      // 154: aaload
      // 155: iload 1
      // 156: putfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.p I
      // 159: aload 6
      // 15b: iload 7
      // 15d: aaload
      // 15e: iload 3
      // 15f: bipush 1
      // 160: isub
      // 161: putfield org/lwjglx/util/glu/tessellation/PriorityQSort$Stack.r I
      // 164: iinc 7 1
      // 167: iload 4
      // 169: bipush 1
      // 16a: iadd
      // 16b: istore 1
      // 16c: goto 08a
      // 16f: iload 1
      // 170: bipush 1
      // 171: iadd
      // 172: istore 3
      // 173: iload 3
      // 174: iload 2
      // 175: if_icmpgt 070
      // 178: aload 0
      // 179: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 17c: iload 3
      // 17d: iaload
      // 17e: istore 5
      // 180: iload 3
      // 181: istore 4
      // 183: iload 4
      // 185: iload 1
      // 186: if_icmple 1be
      // 189: aload 0
      // 18a: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.leq Lorg/lwjglx/util/glu/tessellation/PriorityQ$Leq;
      // 18d: aload 0
      // 18e: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.keys [Ljava/lang/Object;
      // 191: aload 0
      // 192: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 195: iload 4
      // 197: bipush 1
      // 198: isub
      // 199: iaload
      // 19a: aaload
      // 19b: aload 0
      // 19c: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.keys [Ljava/lang/Object;
      // 19f: iload 5
      // 1a1: aaload
      // 1a2: invokestatic org/lwjglx/util/glu/tessellation/PriorityQSort.LT (Lorg/lwjglx/util/glu/tessellation/PriorityQ$Leq;Ljava/lang/Object;Ljava/lang/Object;)Z
      // 1a5: ifeq 1be
      // 1a8: aload 0
      // 1a9: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 1ac: iload 4
      // 1ae: aload 0
      // 1af: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 1b2: iload 4
      // 1b4: bipush 1
      // 1b5: isub
      // 1b6: iaload
      // 1b7: iastore
      // 1b8: iinc 4 -1
      // 1bb: goto 183
      // 1be: aload 0
      // 1bf: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.order [I
      // 1c2: iload 4
      // 1c4: iload 5
      // 1c6: iastore
      // 1c7: iinc 3 1
      // 1ca: goto 173
      // 1cd: aload 0
      // 1ce: aload 0
      // 1cf: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.size I
      // 1d2: putfield org/lwjglx/util/glu/tessellation/PriorityQSort.max I
      // 1d5: aload 0
      // 1d6: bipush 1
      // 1d7: putfield org/lwjglx/util/glu/tessellation/PriorityQSort.initialized Z
      // 1da: aload 0
      // 1db: getfield org/lwjglx/util/glu/tessellation/PriorityQSort.heap Lorg/lwjglx/util/glu/tessellation/PriorityQHeap;
      // 1de: invokevirtual org/lwjglx/util/glu/tessellation/PriorityQHeap.pqInit ()Z
      // 1e1: pop
      // 1e2: bipush 1
      // 1e3: ireturn