Fix(kclvm-parser): return loading file failed error message from meth…

[zong-zhe]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

issue #236

2. What is the scope of this PR (e.g. component or file name):

kclvm-parser

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

Use match replace unwrap.
And the error of loading the file is returned by the return value.

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

6. Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[coveralls]

Pull Request Test Coverage Report for Build 3231683001

• 12 of 13 (92.31%) changed or added relevant lines in 2 files are covered.
• 150 unchanged lines in 6 files lost coverage.
• Overall coverage increased (+0.3%) to 60.111%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/parser/src/parser/tests.rs	6	7	85.71%

Files with Coverage Reduction	New Missed Lines	%
kclvm/runner/src/assembler.rs	1	97.86%
kclvm/sema/src/ty/context.rs	1	93.2%
kclvm/sema/src/resolver/node.rs	9	75.23%
kclvm/sema/src/resolver/config.rs	42	79.61%
kclvm/3rdparty/rustc_span/src/analyze_source_file.rs	48	75.26%
kclvm/parser/src/lib.rs	49	85.2%

Totals
Change from base Build 3226038526:	0.3%
Covered Lines:	21964
Relevant Lines:	36539

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💛 - Coveralls

[Peefy]

LGTM

[chai2010]

LGTM