[fix] Fix white screen when error handled by AppErrorBoundary (#5017)

[In a previous PR](https://github.com/twentyhq/twenty/pull/5008) I was
fixing dark mode by calling useTheme in AppErrorBoundary while there was
actually no parent ThemeProvider. This was causing a bug when an error
was actually intercepted by AppErrorBoundary because theme was empty.

Now I am providing the error theme in GenericErrorFallback, fallbacking
to THEME_LIGHT as it can be called from outside a ThemeProvider (as it
is the case today), but also reading into ThemeProvider in case we end
up using this component in a part of the application where it is
available, not to necessarily use THEME_LIGHT.

## How was it tested?
with @thaisguigon 
Locally (dark mode works + error mode works (throwing an error in
RecoilDebugObserver))

packages/twenty-front/src/modules/error-handler/components/AppErrorBoundary.tsx

@@ -1,6 +1,5 @@
 import { ErrorInfo, ReactNode } from 'react';
 import { ErrorBoundary } from 'react-error-boundary';
-import { ThemeProvider, useTheme } from '@emotion/react';
 
 import { GenericErrorFallback } from '@/error-handler/components/GenericErrorFallback';
 
@@ -9,16 +8,12 @@ export const AppErrorBoundary = ({ children }: { children: ReactNode }) => {
     // TODO: log error to Sentry
   };
 
-  const theme = useTheme();
-
   return (
-    <ThemeProvider theme={theme}>
-      <ErrorBoundary
-        FallbackComponent={GenericErrorFallback}
-        onError={handleError}
-      >
-        {children}
-      </ErrorBoundary>
-    </ThemeProvider>
+    <ErrorBoundary
+      FallbackComponent={GenericErrorFallback}
+      onError={handleError}
+    >
+      {children}
+    </ErrorBoundary>
   );
 };