Fix exceptions when searching for invalid regexps

lib/buffer-search.js

@@ -223,7 +223,7 @@ class BufferSearch {
         scanEnd = Point.INFINITY;
       }
 
-      const newMarkers = this.createMarkers(scanStart, scanEnd);
+      const newMarkers = this.createMarkers(scanStart, scanEnd) || [];
       const oldMarkers = this.markers.splice(spliceStart, (spliceEnd - spliceStart) + 1, ...newMarkers);
       for (let oldMarker of oldMarkers) {
         oldMarker.destroy();

lib/find-view.coffee

@@ -371,7 +371,7 @@ class FindView extends View
 
   firstMarkerIndexAfterCursor: (indexIncluded=false) ->
     editor = @model.getEditor()
-    return null unless editor
+    return null unless editor and @markers?.length > 0
 
     selection = editor.getLastSelection()
     {start, end} = selection.getBufferRange()

spec/find-view-spec.coffee

@@ -1222,6 +1222,19 @@ describe 'FindView', ->
         atom.commands.dispatch(findView.findEditor.element, 'core:confirm')
         expect(getResultDecorations(editor, 'find-result')).toHaveLength 0
 
+  it "doesn't throw an exception when toggling the regex option with an invalid pattern before performing any other search (regression)", ->
+    atom.commands.dispatch editorView, 'find-and-replace:show'
+
+    waitsForPromise ->
+      activationPromise
+
+    runs ->
+      findView.findEditor.setText '('
+      atom.commands.dispatch(findView.findEditor.element, 'find-and-replace:toggle-regex-option')
+
+      editor.insertText('hi')
+      advanceClock(editor.getBuffer().stoppedChangingDelay)
+
   describe "replacing", ->
     beforeEach ->
       editor.setCursorBufferPosition([2, 0])