"Ada allows for errors just as well."

    Although the source of the Operand Error has been 
    identified, this in itself did not cause the mission to 
    fail. The specification of the exception-handling 
    mechanism also contributed to the failure. In the event 
    of any kind of exception, the system specification 
    stated that: the failure should be indicated on the 
    databus, the failure context should be stored in an 
    EEPROM memory (which was recovered and read out for 
    Ariane 501), and finally, the SRI processor should be 
    shut down.

In any case, I'd argue that converting a 64-bit float into a 16-bit integer is a much different class of problem from mixing up assignment and comparison operators. But yes, you're right, even Ada is not perfect.

"Besides, they do rockets in C just as well (with certain rules)."

Yes, they do. Those "certain rules" are codified in the MISRA C standard (or derivatives thereof, like with the JPL and JSF coding standards). Said standard is way more strict than the sort of thing normally implied by "C programming".