fix errors in nfa_to_dot by catching errors in e_regexp + other stuff

tests/basic/loop3.e.expect_14_12_3_8_12

+{"output": "", "error": null, "retval": 128}
\ No newline at end of file

tests/basic/loop3.e.expect_1_2_3

+{"output": "", "error": null, "retval": 128}
\ No newline at end of file

tests/basic/loop4.e

+main(){
+  i = 10;
+  a = 2;
+  res = 0;
+  while(i > 0){
+    x = a + a;
+    y = 1 + x;
+    if(i > 4){
+      res = res + x;
+    } else {
+      if (i < 2){
+        res = res - y;
+      } else {
+        res = res + x - y;
+      }
+    }
+    i = i - 1;
+  }
+  return res;
+}

tests/basic/loop4.e.expect_14_12_3_8_12

+{"output": "", "error": null, "retval": 16}
\ No newline at end of file

tests/basic/loop4.e.expect_1_2_3

+{"output": "", "error": null, "retval": 16}
\ No newline at end of file

tests/test.py

@@ -21,6 +21,7 @@ parser.add_argument("-p", "--passes",
                     nargs='+',
                     default=["e-run",
                              "cfg-run",
+                             "cfg-run-after-loop",
                              "cfg-run-after-cp",
                              "cfg-run-after-dae",
                              "cfg-run-after-ne",