Fix: some post form errors (#5212)

* Fix: type mismatch in post-form-attaches

* Fix: 'this is null' in post-form-window

src/client/app/common/views/components/post-form-attaches.vue

@@ -36,7 +36,7 @@ export default Vue.extend({
 			required: true
 		},
 		detachMediaFn: {
-			type: Object,
+			type: Function,
 			required: false
 		}
 	},

src/client/app/desktop/views/components/post-form-window.vue

@@ -5,8 +5,8 @@
 			<span class="icon" v-if="geo"><fa icon="map-marker-alt"/></span>
 			<span v-if="!reply">{{ $t('note') }}</span>
 			<span v-if="reply">{{ $t('reply') }}</span>
-			<span class="count" v-if="files.length != 0">{{ this.$t('attaches').replace('{}', files.length) }}</span>
-			<span class="count" v-if="uploadings.length != 0">{{ this.$t('uploading-media').replace('{}', uploadings.length) }}<mk-ellipsis/></span>
+			<span class="count" v-if="files.length != 0">{{ $t('attaches').replace('{}', files.length) }}</span>
+			<span class="count" v-if="uploadings.length != 0">{{ $t('uploading-media').replace('{}', uploadings.length) }}<mk-ellipsis/></span>
 		</span>
 	</template>