Python's soft static type rules and extremely flexible variable instantiation unfortunately turns every line of code into a potential runtime error, because the code can't know at compile time if a variable was introduced to the global context that could bind to any given name. Typos are therefore deadly at runtime in Python in a way that they fundamentally aren't in other languages; if you try to write

foo = 0

if foh == 1: # oh no, I misspelled the variable

... many languages (including F#) will fail to compile the program because 'foh is uninitialized.' Python can't know if 'foh' is intended to be a global variable and so will execute the program and only determine while evaluating that line that 'foh' doesn't exist. This is especially insidious in error handling, where the error codepath isn't necessarily exercised; essentially, Python's flexibility implies that if your unit tests don't have 100% line coverage, you can't even know if your program is basically devoid of simple variable typos naming never-existing variables (a check most languages give you for free).

In a language with that feature, a rich ecosystem of exceptions is almost necessary, because every line of code could hide a runtime exception!