Octave: error() must be called with an argument

Examples/test-suite/octave/smart_pointer_extend_runme.m

@@ -9,7 +9,7 @@ f = Foo();
 b = Bar(f);
 
 if (b.extension() != f.extension())
-  error
+  error("failed");
 endif
 
 
@@ -18,15 +18,15 @@ d = CDerived();
 p = CPtr();
 
 if (b.bar() != p.bar())
-  error
+  error("failed");
 endif
 
 if (d.foo() != p.foo())
-  error
+  error("failed");
 endif
 
 if (b.hello() != p.hello())
-  error
+  error("failed");
 endif
 
 
@@ -36,11 +36,11 @@ d = DFoo();
 dp = DPtrFoo(d);
 
 if (d.SExt(1) != dp.SExt(1))
-  error
+  error("failed");
 endif
 
 if (d.Ext(1) != dp.Ext(1))
-  error
+  error("failed");
 endif