Fix crash due to bad rounding in BarChart when no y_step was provided and the max y value was close to 0

manim/mobject/graphing/probability.py

@@ -280,7 +280,13 @@ def __init__(
             ]
 
         elif len(y_range) == 2:
-            y_range = [*y_range, round(max(self.values) / y_length, 2)]
+            y_step_target = max(self.values) / y_length
+            # Round the step size to a suitable (ceil) number of decimal places based on its magnitude (log10(x)). Avoids step size of 0.
+            # At least 2 decimals will be used in the case of large numbers.
+            y_range = [
+                *y_range,
+                round(y_step_target, max(2, int(np.ceil(-np.log10(y_step_target))))),
+            ]
 
         if x_length is None:
             x_length = min(len(self.values), config.frame_width - 2)

tests/module/mobject/graphing/test_bar_chart.py

@@ -0,0 +1,15 @@
+from manim.mobject.graphing.probability import BarChart
+
+
+def test_values_close_to_zero():
+    """Checks that BarChart supports values/heights close to zero without crashing if ."""
+    values = [1 / 10000 for _ in range(8)]
+    names = list(range(len(values)))
+    chart = BarChart(
+        values=values,
+        bar_names=["one", "two", "three", "four", "five"],
+        y_range=[0, 2 / 10000],
+        y_length=6,
+        x_length=10,
+        x_axis_config={"font_size": 36},
+    )