Additional check for Troe coefficients being zero

This will prevent floating point exceptions (sometimes enabled by third-party
codes) in case c[1] or c[2] are zero but will not change the current behaviour
if c[1] and c[2] are not zero.

src/kinetics/Falloff.cpp

@@ -30,8 +30,18 @@ void Troe::init(const vector_fp& c)
             c.size());
     }
     m_a = c[0];
-    m_rt3 = 1.0/c[1];
-    m_rt1 = 1.0/c[2];
+    if (std::abs(c[1]) < SmallNumber) {
+        m_rt3 = std::numeric_limits<double>::infinity();
+    } else {
+        m_rt3 = 1.0 / c[1];
+    }
+
+    if (std::abs(c[2]) < SmallNumber) {
+        m_rt1 = std::numeric_limits<double>::infinity();
+    } else {
+        m_rt1 = 1.0 / c[2];
+    }
+
     if (c.size() == 4) {
         m_t2 = c[3];
     }