Fixed #10481 (misra.py: Bailing out from checking test.c since there was an internal error: Failed to ...)

addons/misra.py

@@ -2150,7 +2150,8 @@ class MisraChecker:
                     self.reportError(token, 10, 2)
 
             if token.str == '-':
-                if getEssentialType(token.astOperand1).split(' ')[-1] != 'char':
+                e1 = getEssentialType(token.astOperand1)
+                if e1 and e1.split(' ')[-1] != 'char':
                     self.reportError(token, 10, 2)
                 if not isEssentiallyChar(token.astOperand2) and not isEssentiallySignedOrUnsigned(token.astOperand2):
                     self.reportError(token, 10, 2)

addons/test/misra/misra-test.c

@@ -677,6 +677,10 @@ static void misra_10_2(void) {
 
     res = s16a - 'a'; // 10.2 10.3 10.4
     res = '0' + f32a; // 10.2 10.4
+
+    // 10481 - crash
+    char buf[1] = {'f'};
+    x = buf[0] - '0';
 }
 
 static void misra_10_3(uint32_t u32a, uint32_t u32b) {