strip out file path from error messages

devNotes/sugarcube stuff/building sugarcube.txt

@@ -40,7 +40,7 @@ Find result files in the dist directory.
 
 Patching
 create a new patch with
-git apply <full path to sugarcube-fc-changes.patch>
+git diff HEAD > <full path to sugarcube-fc-changes.patch>
 Make sure to stage new files first as otherwise they are lost.
 
 APPENDIX Lists required steps very briefly.

devNotes/sugarcube stuff/sugarcube-fc-changes.patch

@@ -11,7 +11,7 @@ index 7a17935..565faa3 100644
  			'src/lib/simplestore/adapters/cookie.js',
  			'src/lib/debugview.js',
 diff --git a/src/lib/helpers.js b/src/lib/helpers.js
-index 2c0157e..f29d190 100644
+index 2c0157e..0448427 100644
 --- a/src/lib/helpers.js
 +++ b/src/lib/helpers.js
 @@ -248,7 +248,7 @@ var { // eslint-disable-line no-var
@@ -31,7 +31,7 @@ index 2c0157e..f29d190 100644
 +			const lines = stack.split('\n');
 +			for (const ll of lines) {
 +				const div = document.createElement('div');
-+				div.append(ll);
++				div.append(ll.replace(/file:.*\//, '<path>/'));
 +				$source.append(div);
 +			}
 +		}
@@ -283,7 +283,7 @@ index d179d9c..265ce5d 100644
  	}
  
 diff --git a/src/macros/macrolib.js b/src/macros/macrolib.js
-index e9500f4..b1d3980 100644
+index e9500f4..6108297 100644
 --- a/src/macros/macrolib.js
 +++ b/src/macros/macrolib.js
 @@ -89,7 +89,7 @@
@@ -304,6 +304,15 @@ index e9500f4..b1d3980 100644
  			}
  		}
  	});
+@@ -493,7 +493,7 @@
+ 				}
+ 			}
+ 			catch (ex) {
+-				return this.error(`bad conditional expression in <<${i === 0 ? 'if' : 'elseif'}>> clause${i > 0 ? ' (#' + i + ')' : ''}: ${typeof ex === 'object' ? ex.message : ex}`); // eslint-disable-line prefer-template
++				return this.error(`bad conditional expression in <<${i === 0 ? 'if' : 'elseif'}>> clause${i > 0 ? ' (#' + i + ')' : ''}: ${typeof ex === 'object' ? `${ex.name}: ${ex.message}` : ex}`, null, ex.stack); // eslint-disable-line prefer-template
+ 			}
+ 		}
+ 	});
 diff --git a/src/markup/wikifier.js b/src/markup/wikifier.js
 index e206f96..61381f0 100644
 --- a/src/markup/wikifier.js