fix nest gemspec dependency (#599)

this patch fix following problem, make nest gem dependency more robustness

1. gemspec dependency should prefer bundle version, not the global gem version
2. capture nest no yardoc error, avoid lost all gem dependency yardoc

refactor:

unify yardoc pins load for root and dependencies

lib/solargraph/yard_map.rb

@@ -214,30 +214,7 @@ def process_requires
           pins.concat cached
           next
         end
-        result = []
-        begin
-          spec = spec_for_require(r)
-          if @source_gems.include?(spec.name)
-            next
-          end
-          next if @gem_paths.key?(spec.name)
-          yd = yardoc_file_for_spec(spec)
-          # YARD detects gems for certain libraries that do not have a yardoc
-          # but exist in the stdlib. `fileutils` is an example. Treat those
-          # cases as errors and check the stdlib yardoc.
-          if yd.nil?
-            process_error(r, result, already_errored, nil)
-            next
-          end
-          @gem_paths[spec.name] = spec.full_gem_path
-          unless yardocs.include?(yd)
-            yardocs.unshift yd
-            result.concat process_yardoc yd, spec
-            result.concat add_gem_dependencies(spec) if with_dependencies?
-          end
-        rescue Gem::LoadError, NoYardocError
-          process_error(r, result, already_errored)
-        end
+        result = pins_for_require r, already_errored
         result.delete_if(&:nil?)
         unless result.empty?
           cache.set_path_pins r, result
@@ -273,31 +250,36 @@ def process_gemsets
       require_from_bundle(directory)
     end
 
-    # @param spec [Gem::Specification]
-    # @return [void]
-    def add_gem_dependencies spec
+    # @param r [String]
+    def pins_for_require r, already_errored
       result = []
-      (spec.dependencies - spec.development_dependencies).each do |dep|
-        begin
-          next if @source_gems.include?(dep.name) || @gem_paths.key?(dep.name)
-          depspec = Gem::Specification.find_by_name(dep.name)
-          next if depspec.nil?
-          @gem_paths[depspec.name] = depspec.full_gem_path
-          gy = yardoc_file_for_spec(depspec)
-          if gy.nil?
-            missing_docs.push dep.name
-          else
-            next if yardocs.include?(gy)
-            yardocs.unshift gy
-            result.concat process_yardoc gy, depspec
-            result.concat add_gem_dependencies(depspec)
+      begin
+        name = r.split('/').first
+        return [] if @source_gems.include?(name) || @gem_paths.key?(name)
+        spec = spec_for_require(name)
+        @gem_paths[name] = spec.full_gem_path
+
+        yd = yardoc_file_for_spec(spec)
+        # YARD detects gems for certain libraries that do not have a yardoc
+        # but exist in the stdlib. `fileutils` is an example. Treat those
+        # cases as errors and check the stdlib yardoc.
+        if yd.nil?
+          process_error(r, result, already_errored, nil)
+          return []
+        end
+        unless yardocs.include?(yd)
+          yardocs.unshift yd
+          result.concat process_yardoc yd, spec
+          if with_dependencies?
+            (spec.dependencies - spec.development_dependencies).each do |dep|
+              result.concat pins_for_require dep.name, already_errored
+            end
           end
-        rescue Gem::LoadError
-          # This error probably indicates a bug in an installed gem
-          Solargraph::Logging.logger.warn "Failed to resolve #{dep.name} gem dependency for #{spec.name}"
         end
+      rescue Gem::LoadError, NoYardocError
+        process_error(r, result, already_errored)
       end
-      result
+      return result
     end
 
     # @param y [String, nil]