Medium Apprentice SpeedRun maps zero-values panics

Go: Reading From a Nil Map

+170 XP · 4 min · attempt 1

Problem

Consider:

    var m map[string]int          // nil map, never make()'d
    v := m["missing"]              // line A: read
    m["x"] = 1                     // line B: write

Which line crashes? Answer with one of: `A`, `B`, `both`, or `neither`.

Starter

// Reading from a nil map returns the zero value silently.
// Writing to a nil map panics with: assignment to entry in nil map.

Your answer

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