Fix some potential after-dispose crashes

src/Program.spec.ts

@@ -44,6 +44,15 @@ describe('Program', () => {
         program.dispose();
     });
 
+    it('does not throw exception after calling validate() after dispose()', () => {
+        program.setFile('source/themes/alpha.bs', `
+            sub main()
+            end sub
+        `);
+        program.dispose();
+        program.validate();
+    });
+
     it('Does not crash for file not referenced by any other scope', async () => {
         program.setFile('tests/testFile.spec.bs', `
             function main(args as object) as object

src/Scope.ts

@@ -562,7 +562,7 @@ export class Scope {
 
         //get callables from own files
         this.enumerateOwnFiles((file) => {
-            for (let callable of file.callables) {
+            for (let callable of file?.callables ?? []) {
                 result.push({
                     callable: callable,
                     scope: this
@@ -843,7 +843,7 @@ export class Scope {
      * Find various function collisions
      */
     private diagnosticDetectFunctionCollisions(file: BscFile) {
-        for (let func of file.callables) {
+        for (let func of file?.callables ?? []) {
             const funcName = func.getName(ParseMode.BrighterScript);
             const lowerFuncName = funcName?.toLowerCase();
             if (lowerFuncName) {
@@ -932,7 +932,7 @@ export class Scope {
      */
     private diagnosticDetectFunctionCallsWithWrongParamCount(file: BscFile, callableContainersByLowerName: CallableContainerMap) {
         //validate all function calls
-        for (let expCall of file.functionCalls) {
+        for (let expCall of file?.functionCalls ?? []) {
             let callableContainersWithThisName = callableContainersByLowerName.get(expCall.name.toLowerCase());
 
             //use the first item from callablesByLowerName, because if there are more, that's a separate error

src/bscPlugin/validation/ScopeValidator.ts

@@ -269,7 +269,7 @@ export class ScopeValidator {
     protected validateCreateObjectCalls(file: BrsFile) {
         const diagnostics: BsDiagnostic[] = [];
 
-        for (const call of file.functionCalls) {
+        for (const call of file?.functionCalls ?? []) {
             //skip non CreateObject function calls
             if (call.name?.toLowerCase() !== 'createobject' || !isLiteralExpression(call?.args[0]?.expression)) {
                 continue;

src/lsp/ProjectManager.ts

@@ -72,8 +72,6 @@ export class ProjectManager {
      */
     @TrackBusyStatus
     private async flushDocumentChanges(event: FlushEvent) {
-        this.logger.log('flushDocumentChanges', event.actions.map(x => x.srcPath));
-
         //ensure that we're fully initialized before proceeding
         await this.onInitialized();