fix(net/ghttp): panic when post empty string parameter to *ghttp.UploadFile

[gqcn]

fixed #4193

[gqcn]

related #4203

[hailaz]

@gqcn 过不了单测

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@gqcn Can't pass the single test

[Copilot]

Pull Request Overview

This PR fixes a panic that occurs when posting an empty string parameter to *ghttp.UploadFile by improving handling of empty values in the type conversion system. The fix addresses issue #4193 where empty strings were causing conversion failures that led to panics.

• Adds early return handling for empty strings in float conversion functions
• Updates error handling in struct conversion to properly propagate errors instead of suppressing them
• Modifies map conversion logic to return empty maps when mustMapReturn is true for empty inputs
• Changes default error handling behavior in Scan function to fail fast instead of continuing on errors

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
util/gconv/internal/converter/converter_struct.go	Updates error message format and removes fallback conversion that was masking errors
util/gconv/internal/converter/converter_map.go	Adds handling for empty strings/bytes to return empty maps when required
util/gconv/internal/converter/converter_float.go	Adds empty string checks to return 0 instead of attempting invalid parsing
util/gconv/internal/converter/converter_convert.go	Minor variable declaration style change and comment correction
util/gconv/gconv_scan.go	Changes default ContinueOnError from true to false for better error visibility
net/ghttp/ghttp_z_unit_issue_test.go	Adds test case for the fixed issue and corrects indentation

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