Unexpected path of execution

[Charles Hixson]

given this code fragment:

             if    (i < (line.length - 3) )
             {    writeln ("in c4: i = ", i, ", line.length = ", 
line.length);
                   add2 (c4, line [i..i+4]);
I get this result:

in c4: i = 0, line.length = 2
core.exception.RangeError at source/freqs.d(32): Range violation
----------------
??:? _d_arrayboundsp [0x56041325a70d]
??:? _Dmain [0x560413233beb]

Why did this get executed?  The if test was supposed to prevent this.

DMD64 D Compiler v2.097.2

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