[ck2cti] Detect badly formatted values of 4th Troe coefficient

Fixes #499

interfaces/cython/cantera/ck2cti.py

@@ -1390,10 +1390,7 @@ class Parser(object):
                 alpha = float(tokens[0].strip())
                 T3 = float(tokens[1].strip())
                 T1 = float(tokens[2].strip())
-                try:
-                    T2 = float(tokens[3].strip())
-                except (IndexError, ValueError):
-                    T2 = None
+                T2 = float(tokens[3].strip()) if len(tokens) > 3 else None
 
                 falloff = Troe(
                     alpha=(alpha,''),

interfaces/cython/cantera/test/test_convert.py

@@ -278,6 +278,12 @@ class chemkinConverterTest(utilities.CanteraTest):
                                         'explicit-forward-order.cti')
         self.checkKinetics(ref, gas, [300, 800, 1450, 2800], [5e3, 1e5, 2e6])
 
+    def test_bad_troe_value(self):
+        with self.assertRaises(ValueError):
+            convertMech(pjoin(self.test_data_dir, 'bad-troe.inp'),
+                        thermoFile=pjoin(self.test_data_dir, 'dummy-thermo.dat'),
+                        outName=pjoin(self.test_work_dir, 'bad-troe.cti'), quiet=True)
+
     def test_reaction_units(self):
         convertMech(pjoin(self.test_data_dir, 'units-default.inp'),
                     thermoFile=pjoin(self.test_data_dir, 'dummy-thermo.dat'),

test/data/bad-troe.inp

@@ -0,0 +1,13 @@
+ELEMENTS
+H  C
+END
+
+SPECIES
+H R1A R1B P1
+END
+
+REACTIONS
+R1A+R1B(+M) <=> H+P1(+M)                     1e12  0.0  20000.0
+     LOW  /  1.040E+26   -2.760   1600.00/
+     TROE/   .5620  91.00  5836.00  1.00000+100/
+END