Handle message rendering errors via the errorCaptured hook

Also, fix some issues with uploads on iOS

src/components/MessageErrorHandler.vue

@@ -0,0 +1,29 @@
+
+<template>
+  <div>
+    <slot
+      v-if="err"
+      name="error"
+      v-bind:err="err"
+    ><div class="text-center">{{ $t('message.failed_to_render') }}</div></slot>
+    <slot v-else></slot>
+  </div>
+</template>
+
+<script>
+export default {
+  name: "MessageErrorHandler",
+  data() {
+    return {
+      err: false,
+    };
+  },
+  errorCaptured(err, ignoredvm, ignoredinfo) {
+    this.err = err;
+    return false;
+  }
+};
+</script>
+
+<style lang="scss" scoped>
+</style>