Add safety checks for go casts in the interpreter

[dsainati1]

Description

This adds more graceful go handling for some type assertions in the runtime/sema directory, which previously were unhandled. This should not result in any behavioral differences. Part of https://github.com/dapperlabs/cadence-private-issues/issues/4

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• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov-commenter]

Codecov Report

Merging #1331 (0e213e7) into master (834f5f1) will decrease coverage by 0.26%.
The diff coverage is 44.01%.

@@            Coverage Diff             @@
##           master    #1331      +/-   ##
==========================================
- Coverage   75.57%   75.30%   -0.27%     
==========================================
  Files         279      279              
  Lines       37813    37934     +121     
==========================================
- Hits        28578    28568      -10     
- Misses       7958     8030      +72     
- Partials     1277     1336      +59     

Flag	Coverage Δ
unittests	75.30% <44.01%> (-0.27%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
runtime/interpreter/value.go	68.44% <39.13%> (-0.52%)	⬇️
runtime/interpreter/interpreter.go	88.01% <39.62%> (-1.60%)	⬇️
runtime/interpreter/interpreter_expression.go	81.78% <48.48%> (-9.40%)	⬇️
runtime/interpreter/interpreter_statement.go	86.44% <53.84%> (-2.26%)	⬇️

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[github-actions]

Cadence Benchstat comparison

This branch with compared with the base branch onflow:master commit 834f5f1
The command for i in {1..N}; do go test ./... -run=XXX -bench=. -shuffle=on; done was used.
Bench tests were run a total of 7 times on each branch.

Results

	old.txt	new.txt
	time/op		delta
RuntimeResourceDictionaryValues-2	13.6ms ± 2%	13.4ms ± 7%	~	(p=0.165 n=7+7)
RuntimeFungibleTokenTransfer-2	1.12ms ±20%	1.16ms ±18%	~	(p=1.000 n=7+7)
ParseDeploy/byte_array-2	33.5ms ± 3%	33.2ms ± 1%	~	(p=0.534 n=7+6)
ParseDeploy/decode_hex-2	1.16ms ± 1%	1.16ms ± 0%	~	(p=0.268 n=7+5)
ParseArray-2	22.5ms ± 3%	22.1ms ± 2%	~	(p=0.053 n=7+7)
ParseFungibleToken-2	439µs ± 4%	436µs ± 2%	~	(p=0.710 n=7+7)
ParseInfix-2	23.6µs ± 4%	23.7µs ± 2%	~	(p=0.456 n=7+7)
QualifiedIdentifierCreation/One_level-2	2.83ns ± 2%	2.81ns ± 0%	~	(p=0.803 n=6+6)
QualifiedIdentifierCreation/Three_levels-2	120ns ± 2%	120ns ± 1%	~	(p=0.472 n=6+7)
CheckContractInterfaceFungibleTokenConformance-2	129µs ± 1%	128µs ± 2%	~	(p=0.234 n=6+7)
ContractInterfaceFungibleToken-2	40.0µs ± 1%	39.6µs ± 1%	~	(p=0.132 n=6+6)
InterpretRecursionFib-2	2.53ms ± 4%	2.48ms ± 1%	~	(p=0.534 n=7+6)
NewInterpreter/new_interpreter-2	967ns ± 1%	965ns ± 1%	~	(p=0.699 n=6+6)
NewInterpreter/new_sub-interpreter-2	2.11µs ± 5%	2.05µs ± 1%	−2.63%	(p=0.019 n=7+7)
	alloc/op		delta
RuntimeResourceDictionaryValues-2	4.04MB ± 0%	4.04MB ± 0%	~	(p=0.383 n=7+7)
RuntimeFungibleTokenTransfer-2	238kB ± 0%	238kB ± 0%	~	(p=0.646 n=7+7)
QualifiedIdentifierCreation/One_level-2	0.00B	0.00B	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	64.0B ± 0%	64.0B ± 0%	~	(all equal)
CheckContractInterfaceFungibleTokenConformance-2	65.7kB ± 0%	65.7kB ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	26.5kB ± 0%	26.5kB ± 0%	~	(all equal)
InterpretRecursionFib-2	1.24MB ± 0%	1.24MB ± 0%	~	(p=0.972 n=6+7)
NewInterpreter/new_interpreter-2	720B ± 0%	720B ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	1.18kB ± 0%	1.18kB ± 0%	~	(all equal)
	allocs/op		delta
RuntimeResourceDictionaryValues-2	102k ± 0%	102k ± 0%	~	(p=0.718 n=7+7)
RuntimeFungibleTokenTransfer-2	4.54k ± 0%	4.54k ± 0%	~	(p=0.700 n=7+7)
QualifiedIdentifierCreation/One_level-2	0.00	0.00	~	(all equal)
QualifiedIdentifierCreation/Three_levels-2	2.00 ± 0%	2.00 ± 0%	~	(all equal)
CheckContractInterfaceFungibleTokenConformance-2	1.07k ± 0%	1.07k ± 0%	~	(all equal)
ContractInterfaceFungibleToken-2	457 ± 0%	457 ± 0%	~	(all equal)
InterpretRecursionFib-2	25.0k ± 0%	25.0k ± 0%	~	(all equal)
NewInterpreter/new_interpreter-2	11.0 ± 0%	11.0 ± 0%	~	(all equal)
NewInterpreter/new_sub-interpreter-2	36.0 ± 0%	36.0 ± 0%	~	(all equal)

[turbolent]

Looks good! 👍