fix regression reported at https://www.wilderssecurity.com/threads/umatrix-the-http-switchboard-successor.369601/page-27#post-2737419

src/js/matrix.js

@@ -685,9 +685,8 @@ Matrix.prototype.fromLine = function(line) {
     let field0 = fields[0];
 
     // Switches
-    let pos = field0.indexOf(':');
+    if ( this.reSwitchRule.test(field0) ) {
-    if ( pos !== -1 ) {
+        let switchName = field0.slice(0, -1);
-        let switchName = field0.slice(0, pos);
         let srcHostname = punycode.toASCII(fields[1]);
         let state = fields[2];
         if (
@@ -736,6 +735,8 @@ Matrix.prototype.fromLine = function(line) {
     return true;
 };
 
+Matrix.prototype.reSwitchRule = /^[0-9a-z-]+:$/;
+
 /******************************************************************************/
 
 Matrix.prototype.toSelfie = function() {