Added code to prevent "variable possibly unbound" error from propagating to other variables. It should be reported only once.

server/src/analyzer/typeEvaluator.ts

@@ -2440,6 +2440,11 @@ export function createTypeEvaluator(importLookup: ImportLookup, printTypeFlags:
             }
         }
 
+        // If the type was partially unbound, an error will have already been logged.
+        // Remove the unbound before assigning to the target expression so the unbound
+        // error doesn't propagate.
+        type = removeUnboundFromUnion(type);
+
         switch (target.nodeType) {
             case ParseNodeType.Name: {
                 const name = target;

server/src/tests/checker.test.ts

@@ -1104,6 +1104,12 @@ test('Unbound2', () => {
     validateResults(analysisResults, 1);
 });
 
+test('Unbound3', () => {
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['unbound3.py']);
+
+    validateResults(analysisResults, 1);
+});
+
 test('UnnecessaryCast', () => {
     const configOptions = new ConfigOptions('.');
 

server/src/tests/samples/unbound3.py

@@ -0,0 +1,14 @@
+# This sample tests that "possibly unbound" error messages don't propagate.
+
+
+def foo(a: bool):
+    if a:
+        b = 3
+
+    # This should generate an error.
+    c = b
+
+    # These should not.
+    d = c
+    e = d
+