fix: return empty array if manifest doesnt have functions defined

[khendrikse]

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Summary

I ran netlify dev with a manifest that had no functions array, and got an error because the functions were actually defined in the toml file.

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[github-actions]

📊 Benchmark results

Comparing with 83a81b1

Package size: 265 MB

(no change)

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└───┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴──>
    T-12    T-11    T-10    T-9     T-8     T-7     T-6     T-5     T-4     T-3     T-2     T-1      T    

Legend

• T-29 (bce1f2c): 260 MB
• T-28 (2d3923c): 260 MB
• T-27 (6726bf4): 267 MB
• T-26 (87adddc): 267 MB
• T-25 (6d6531a): 267 MB
• T-24 (f33c595): 267 MB
• T-23 (6594da7): 267 MB
• T-22 (22ecec6): 260 MB
• T-21 (c7c5fff): 267 MB
• T-20 (7e27e7a): 267 MB
• T-19 (89754a1): 267 MB
• T-18 (2aa9341): 267 MB
• T-17 (734c23c): 267 MB
• T-16 (e978613): 267 MB
• T-15 (733c47e): 267 MB
• T-14 (027efcf): 267 MB
• T-13 (99305de): 267 MB
• T-12 (3a9670b): 267 MB
• T-11 (f9ff366): 267 MB
• T-10 (384e168): 272 MB
• T-9 (a0f3719): 272 MB
• T-8 (8146b3d): 272 MB
• T-7 (43e6f9e): 272 MB
• T-6 (4600e9b): 265 MB
• T-5 (b0a6c85): 265 MB
• T-4 (70ef88c): 265 MB
• T-3 (cfcee54): 265 MB
• T-2 (63d415b): 265 MB
• T-1 (83a81b1): 265 MB
• T (current commit): 265 MB

[eduardoboucas]

Presumably this would only be a problem if you ended up with a manifest file that had no functions property. How did that happen?