Correct spelling mistakes

app/client/models/DocData.ts

@@ -34,7 +34,7 @@ export class DocData extends BaseDocData {
 
   /**
    * Constructor for DocData.
-   * @param {Object} docComm: A map of server methods availble on this document.
+   * @param {Object} docComm: A map of server methods available on this document.
    * @param {Object} metaTableData: A map from tableId to table data, presented as an action,
    *      equivalent to BulkAddRecord, i.e. ["TableData", tableId, rowIds, columnValues].
    */

app/client/models/TreeModel.ts

@@ -74,7 +74,7 @@ function getRecords(table: TreeTableData) {
   return fixIndents(records);
 }
 
-// The fixIndents function returns a copy of records with the garantee the .indentation starts at 0
+// The fixIndents function returns a copy of records with the guarantee the .indentation starts at 0
 // and can only increase one step at a time (note that it is however permitted to decrease several
 // level at a time). This is useful to build a model for the tree view.
 export function fixIndents(records: TreeRecord[]) {

app/client/models/errors.ts

@@ -20,7 +20,7 @@ export class UserError extends Error {
 }
 
 /**
- * This error causes Notifer to show the message with an upgrade link.
+ * This error causes Notifier to show the message with an upgrade link.
  */
 export class NeedUpgradeError extends Error {
   public name: string = 'NeedUpgradeError';