refactor error handling part 1 (#307)

- created `getErrorMessage` function which takes in an error string or any type of error object and returns the correct error message
- replaced `error.message` with `getErrorMessage` since `error` could be a string in some cases
- merged sendNotificationForError.ts with ErrorHandlingUtils.ts
- some minor refactoring

In part 2, I will make the following changes:
 - Make `Logger.logError` function take an error message string instead of an error object. This will reduce some redundancy where the `getErrorMessage` function is being called twice (the error object passed by the caller is already an error message).
 - Update every `TelemetryProcessor.traceFailure` call to make sure we pass in an error message instead of an error object since we stringify the data we send.

src/Explorer/Panes/BrowseQueriesPane.ts

@@ -7,6 +7,7 @@ import * as Logger from "../../Common/Logger";
 import { QueriesGridComponentAdapter } from "../Controls/QueriesGridReactComponent/QueriesGridComponentAdapter";
 import * as TelemetryProcessor from "../../Shared/Telemetry/TelemetryProcessor";
 import QueryTab from "../Tabs/QueryTab";
+import { getErrorMessage } from "../../Common/ErrorHandlingUtils";
 
 export class BrowseQueriesPane extends ContextualPaneBase {
   public queriesGridComponentAdapter: QueriesGridComponentAdapter;
@@ -60,17 +61,19 @@ export class BrowseQueriesPane extends ContextualPaneBase {
         startKey
       );
     } catch (error) {
+      const errorMessage = getErrorMessage(error);
       TelemetryProcessor.traceFailure(
         Action.SetupSavedQueries,
         {
           databaseAccountName: this.container && this.container.databaseAccount().name,
           defaultExperience: this.container && this.container.defaultExperience(),
           dataExplorerArea: Areas.ContextualPane,
-          paneTitle: this.title()
+          paneTitle: this.title(),
+          error: errorMessage
         },
         startKey
       );
-      this.formErrors(`Failed to setup a collection for saved queries: ${error.message}`);
+      this.formErrors(`Failed to setup a collection for saved queries: ${errorMessage}`);
     } finally {
       this.isExecuting(false);
     }