Propagate error from EventLoop creation

Inner panics could make it hard to trouble shoot the issues and for some
users ints not desirable.

The inner panics were left only when they are used to `assert!` during
development.

src/platform_impl/android/mod.rs

@@ -30,7 +30,7 @@ use crate::{
         self, CursorGrabMode, ImePurpose, ResizeDirection, Theme, WindowButtons, WindowLevel,
     },
 };
-use crate::{error::RunLoopError, platform_impl::Fullscreen};
+use crate::{error::EventLoopError, platform_impl::Fullscreen};
 
 mod keycodes;
 
@@ -186,13 +186,15 @@ fn sticky_exit_callback<T, F>(
 }
 
 impl<T: 'static> EventLoop<T> {
-    pub(crate) fn new(attributes: &PlatformSpecificEventLoopAttributes) -> Self {
+    pub(crate) fn new(
+        attributes: &PlatformSpecificEventLoopAttributes,
+    ) -> Result<Self, EventLoopError> {
         let (user_events_sender, user_events_receiver) = mpsc::channel();
 
         let android_app = attributes.android_app.as_ref().expect("An `AndroidApp` as passed to android_main() is required to create an `EventLoop` on Android");
         let redraw_flag = SharedFlag::new();
 
-        Self {
+        Ok(Self {
             android_app: android_app.clone(),
             window_target: event_loop::EventLoopWindowTarget {
                 p: EventLoopWindowTarget {
@@ -214,7 +216,7 @@ impl<T: 'static> EventLoop<T> {
             control_flow: Default::default(),
             cause: StartCause::Init,
             ignore_volume_keys: attributes.ignore_volume_keys,
-        }
+        })
     }
 
     fn single_iteration<F>(&mut self, main_event: Option<MainEvent<'_>>, callback: &mut F)
@@ -524,19 +526,19 @@ impl<T: 'static> EventLoop<T> {
         self.pending_redraw = pending_redraw;
     }
 
-    pub fn run<F>(mut self, event_handler: F) -> Result<(), RunLoopError>
+    pub fn run<F>(mut self, event_handler: F) -> Result<(), EventLoopError>
     where
         F: FnMut(event::Event<T>, &event_loop::EventLoopWindowTarget<T>, &mut ControlFlow),
     {
         self.run_ondemand(event_handler)
     }
 
-    pub fn run_ondemand<F>(&mut self, mut event_handler: F) -> Result<(), RunLoopError>
+    pub fn run_ondemand<F>(&mut self, mut event_handler: F) -> Result<(), EventLoopError>
     where
         F: FnMut(event::Event<T>, &event_loop::EventLoopWindowTarget<T>, &mut ControlFlow),
     {
         if self.loop_running {
-            return Err(RunLoopError::AlreadyRunning);
+            return Err(EventLoopError::AlreadyRunning);
         }
 
         loop {
@@ -545,7 +547,7 @@ impl<T: 'static> EventLoop<T> {
                     break Ok(());
                 }
                 PumpStatus::Exit(code) => {
-                    break Err(RunLoopError::ExitFailure(code));
+                    break Err(EventLoopError::ExitFailure(code));
                 }
                 _ => {
                     continue;