fix(mobile): only change screens on location change if not welcome screen

ibi-group/trimet-mod-otp#203

Author: landonreed

lib/actions/form.js

@@ -120,8 +120,14 @@ export function formChanged (oldQuery, newQuery) {
       dispatch(setMainPanelContent(null))
     }
 
-    // Clear the current search and return to search screen on mobile when either location changes
-    if (isMobile() && (fromChanged || toChanged)) {
+    // Clear the current search and return to search screen on mobile when
+    // either location changes only if not currently on welcome screen (otherwise
+    // when the current position is auto-set the screen will change unexpectedly).
+    if (
+      isMobile() &&
+      (fromChanged || toChanged) &&
+      otpState.ui.mobileScreen !== MobileScreens.WELCOME_SCREEN
+    ) {
       dispatch(clearActiveSearch())
       dispatch(setMobileScreen(MobileScreens.SEARCH_FORM))
     }