prevent illegal reassignments, part 2

src/Statement.js

@@ -105,11 +105,9 @@ export default class Statement {
 					return this.skip();
 				}
 
-				if ( isReference( node, parent ) ) {
-					const reference = new Reference( node, scope );
-					references.push( reference );
+				let isReassignment;
 
-					if ( parent.type in modifierNodes ) {
+				if ( parent && parent.type in modifierNodes ) {
 					let subject = parent[ modifierNodes[ parent.type ] ];
 					let depth = 0;
 
@@ -133,10 +131,15 @@ export default class Statement {
 						}
 					}
 
-						reference.isReassignment = !depth;
+					isReassignment = !depth;
 				}
 
+				if ( isReference( node, parent ) ) {
+					const reference = new Reference( node, scope );
+					references.push( reference );
+
 					reference.isImmediatelyUsed = !readDepth;
+					reference.isReassignment = isReassignment;
 
 					this.skip(); // don't descend from `foo.bar.baz` into `foo.bar`
 				}