test: refactor test-stream-pipe-error-handling

* provide a RegExp for second argument to `assert.throws()`
* remove unused function arguments
* provide duration of 1 ms for `setTimeout()` calls that do not have a
  duration

PR-URL: nodejs#10530
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-stream-pipe-error-handling.js

@@ -50,16 +50,16 @@ const Stream = require('stream').Stream;
       assert(removed);
       assert.throws(function() {
         w.emit('error', new Error('fail'));
-      });
-    }));
+      }, /^Error: fail$/);
+    }), 1);
   });
 
   w.on('error', myOnError);
   r.pipe(w);
   w.removeListener('error', myOnError);
   removed = true;
 
-  function myOnError(er) {
+  function myOnError() {
     throw new Error('this should not happen');
   }
 }
@@ -76,10 +76,10 @@ const Stream = require('stream').Stream;
     setTimeout(common.mustCall(function() {
       assert(removed);
       w.emit('error', new Error('fail'));
-    }));
+    }), 1);
   });
 
-  w.on('error', common.mustCall(function(er) {}));
+  w.on('error', common.mustCall(function() {}));
   w._write = function() {};
 
   r.pipe(w);