Fix composer not opening for Pleroma instances

Pleroma doesn't have `configuration` in instance API response

src/components/compose.jsx

@@ -23,6 +23,7 @@ import {
   getCurrentAccount,
   getCurrentAccountNS,
   getCurrentInstance,
+  getCurrentInstanceConfiguration,
 } from '../utils/store-utils';
 import supports from '../utils/supports';
 import useInterval from '../utils/useInterval';
@@ -119,21 +120,30 @@ function Compose({
   const currentAccount = getCurrentAccount();
   const currentAccountInfo = currentAccount.info;
 
-  const { configuration } = getCurrentInstance();
+  const configuration = getCurrentInstanceConfiguration();
   console.log('⚙️ Configuration', configuration);
 
   const {
-    statuses: { maxCharacters, maxMediaAttachments, charactersReservedPerUrl },
+    statuses: {
+      maxCharacters,
+      maxMediaAttachments,
+      charactersReservedPerUrl,
+    } = {},
     mediaAttachments: {
-      supportedMimeTypes,
+      supportedMimeTypes = [],
       imageSizeLimit,
       imageMatrixLimit,
       videoSizeLimit,
       videoMatrixLimit,
       videoFrameRateLimit,
-    },
-    polls: { maxOptions, maxCharactersPerOption, maxExpiration, minExpiration },
-  } = configuration;
+    } = {},
+    polls: {
+      maxOptions,
+      maxCharactersPerOption,
+      maxExpiration,
+      minExpiration,
+    } = {},
+  } = configuration || {};
 
   const textareaRef = useRef();
   const spoilerTextRef = useRef();

src/utils/store-utils.js

@@ -81,3 +81,42 @@ export function getCurrentInstance() {
     return {};
   }
 }
+
+// Massage these instance configurations to match the Mastodon API
+// - Pleroma
+function getInstanceConfiguration(instance) {
+  const {
+    configuration,
+    maxMediaAttachments,
+    maxTootChars,
+    pleroma,
+    pollLimits,
+  } = instance;
+
+  const statuses = configuration?.statuses || {};
+  if (maxMediaAttachments) {
+    statuses.maxMediaAttachments ??= maxMediaAttachments;
+  }
+  if (maxTootChars) {
+    statuses.maxCharacters ??= maxTootChars;
+  }
+
+  const polls = configuration?.polls || {};
+  if (pollLimits) {
+    polls.maxCharactersPerOption ??= pollLimits.maxOptionChars;
+    polls.maxExpiration ??= pollLimits.maxExpiration;
+    polls.maxOptions ??= pollLimits.maxOptions;
+    polls.minExpiration ??= pollLimits.minExpiration;
+  }
+
+  return {
+    ...configuration,
+    statuses,
+    polls,
+  };
+}
+
+export function getCurrentInstanceConfiguration() {
+  const instance = getCurrentInstance();
+  return getInstanceConfiguration(instance);
+}