remove casting from no-unused-message-ids

Author: michaelfaith

lib/rules/no-unused-message-ids.ts

@@ -56,7 +56,7 @@ const rule: Rule.RuleModule = {
         contextIdentifiers = getContextIdentifiers(scopeManager, ast);
       },
 
-      'Program:exit'(ast) {
+      'Program:exit'() {
         if (hasSeenUnknownMessageId || !hasSeenViolationReport) {
           /*
           Bail out when the rule is likely to have false positives.
@@ -107,21 +107,23 @@ const rule: Rule.RuleModule = {
             const values =
               messageId.type === 'Literal'
                 ? [messageId]
-                : findPossibleVariableValues(
-                    messageId as Identifier,
+                : messageId.type === 'Identifier'
+                  ? findPossibleVariableValues(
+                    messageId,
                     scopeManager,
-                  );
+                  ) : [];
             if (
               values.length === 0 ||
               values.some((val) => val.type !== 'Literal')
             ) {
               // When a dynamic messageId is used and we can't detect its value, disable the rule to avoid false positives.
               hasSeenUnknownMessageId = true;
             }
-            values.forEach(
-              (val) =>
-                'value' in val && messageIdsUsed.add(val.value as string),
-            );
+            values
+            .filter(value => value.type === 'Literal')
+            .map(value => value.value)
+            .filter(value => typeof value === 'string')
+            .forEach(value => messageIdsUsed.add(value));
           }
         }
       },