fix cppcoreguidelines-init-variables checks (#1821)

Refs: #1663

Signed-off-by: Balakrishna Avulapati <ba@bavulapati.com>

Author: bavulapati

src/core/json/parser.h

@@ -681,7 +681,7 @@ auto internal_parse_json(
   std::stack<std::reference_wrapper<Result>> frames;
   std::optional<Result> result;
   typename Result::String key{""};
-  typename JSON::Char character;
+  typename JSON::Char character = 0;
 
   /*
    * Parse any JSON document

src/core/jsonpointer/parser.h

@@ -44,7 +44,7 @@ namespace sourcemeta::core {
 auto parse_pointer(std::basic_istream<JSON::Char, JSON::CharTraits> &stream)
     -> Pointer {
   Pointer result;
-  JSON::Char character;
+  JSON::Char character = 0;
   std::basic_stringstream<JSON::Char> string;
   std::uint64_t column{0};
 

src/core/uri/escaping.cc

@@ -75,7 +75,7 @@ auto uri_escape(const char character, std::ostream &output,
 
 auto uri_escape(std::istream &input, std::ostream &output,
                 const URIEscapeMode mode) -> void {
-  char character;
+  char character = 0;
   while (input.get(character)) {
     uri_escape(character, output, mode);
   }

src/core/uri/uri.cc

@@ -23,7 +23,7 @@ auto uri_normalize(UriUriA *uri) -> void {
 }
 
 auto uri_to_string(const UriUriA *const uri) -> std::string {
-  int size;
+  int size = 0;
   if (uriToStringCharsRequiredA(uri, &size) != URI_SUCCESS) {
     throw sourcemeta::core::URIError{"Could not determine URI size"};
   }
@@ -51,7 +51,7 @@ auto uri_text_range(const UriTextRangeA *const range)
 }
 
 auto uri_parse(const std::string &data, UriUriA *uri) -> void {
-  const char *error_position;
+  const char *error_position = nullptr;
   switch (uriParseSingleUriA(uri, data.c_str(), &error_position)) {
     case URI_ERROR_SYNTAX:
       // TODO: Test the positions of this error