Fix Issue 21347 - array literal parser doesn't stop on missing comma

[usefahmed07]

Fixes #21347

[github-actions]

DMD perf check

Metric	Base	PR	Δ
compile hello.d (instr)	214.9 M	231.0 M	+7.489%
compile hello.d -O -release (instr)	233.2 M	249.3 M	+6.893%
compile Phobos (instr)	5,121.9 M	5,182.3 M	+1.180%
compile vibe.d (instr)	15,124.3 M	15,207.4 M	+0.549%
dmd binary size (stripped)	6.86 MB	7.09 MB	+3.30%

Breakdown — compile hello.d

Phase (wall, self time)	Base	PR	Δ
parse	36.9 ms	35.1 ms	-4.91%
sema1	11.9 ms	10.7 ms	-10.38%
sema_other	14.9 ms	14.3 ms	-3.48%
sema3	6.0 ms	6.1 ms	+1.14%
codegen	2.0 ms	2.0 ms	-2.73%

Breakdown — compile Phobos

+60.4 M instructions: frontend +59.8 M (+1.64%), codegen +0.7 M (+0.04%)

Phase (wall, self time)	Base	PR	Δ
sema3	578 ms	594 ms	+2.79%
sema1	226 ms	234 ms	+3.57%
sema_other	203 ms	206 ms	+1.93%
parse	119 ms	117 ms	-1.61%
codegen	413 ms	413 ms	-0.15%
inline	4.6 ms	4.8 ms	+3.97%
ctfe	14.3 ms	14.2 ms	-0.48%
sema2	2.3 ms	2.2 ms	-2.82%

All measurements

Metric	Base	PR	Δ
compile hello.d (instr)	214.9 M	231.0 M	+7.489%
compile hello.d -O -release (instr)	233.2 M	249.3 M	+6.893%
compile Phobos (instr)	5,121.9 M	5,182.3 M	+1.180%
compile Phobos codegen (instr)	1,472.0 M	1,472.7 M	+0.044%
compile vibe.d (instr)	15,124.3 M	15,207.4 M	+0.549%
dmd binary size (stripped)	6.86 MB	7.09 MB	+3.30%
hello binary size (stripped)	0.72 MB	0.72 MB	0.00%
peak RSS (compile hello.d)	43.40 MB	43.62 MB	+0.52%
peak RSS (compile Phobos)	617.4 MB	620.2 MB	+0.44%
peak RSS (compile vibe.d)	1918 MB	1917 MB	-0.03%
compile dmd itself (wall)	12.4 s	12.5 s	+0.52%
compile hello.d (wall)	71.7 ms	68.2 ms	-4.95%
compile Phobos (wall)	1,560 ms	1,585 ms	+1.64%

_{eecd1b2 vs merge-base 52c8c25 · about these metrics}