fix parse() to match spec (return true if valid, false if invalid (and a parseError handler is defined))

src/mermaidAPI.js

@@ -63,12 +63,15 @@ import getStyles from './styles';
 import theme from './themes';
 import utils, { directiveSanitizer, assignWithDepth, sanitizeCss } from './utils';
 import DOMPurify from 'dompurify';
+import mermaid from './mermaid';
 
 /**
  * @param text
  * @returns {any}
  */
 function parse(text) {
+  var parseEncounteredException = false;
+  try {
     text = text + '\n';
     const cnf = configApi.getConfig();
     const graphInit = utils.detectInit(text, cnf);
@@ -155,7 +158,25 @@ function parse(text) {
     };
 
     parser.parse(text);
-  return parser;
+  } catch (error) {
+    parseEncounteredException = true;
+    // Is this the correct way to access mermiad's parseError()
+    // method ? (or global.mermaid.parseError()) ?
+    if (mermaid.parseError) {
+      if (error.str != undefined) {
+        // handle case where error string and hash were
+        // wrapped in object like`const error = { str, hash };`
+        mermaid.parseError(error.str, error.hash);
+      } else {
+        // assume it is just error string and pass it on
+        mermaid.parseError(error);
+      }
+    } else {
+      // No mermaid.parseError() handler defined, so re-throw it
+      throw error;
+    }
+  }
+  return !parseEncounteredException;
 }
 
 export const encodeEntities = function (text) {