Clarify types of errors in spec text

spec/Section 3 -- Type System.md

@@ -95,7 +95,7 @@ a server must not include a type called `Int` and use it to represent
 
 A GraphQL server, when preparing a field of a given scalar type, must uphold the
 contract the scalar type describes, either by coercing the value or
-producing an error.
+producing a field error.
 
 For example, a GraphQL server could be preparing a field with the scalar type
 `Int` and encounter a floating-point number. Since the server must not break the
@@ -805,13 +805,13 @@ An input object is never a valid result.
 **Input Coercion**
 
 The value for an input object should be an input object literal or an unordered
-map, otherwise an error should be thrown. This unordered map should not contain
+map, otherwise a query error should be thrown. This unordered map should not contain
 any entries with names not defined by a field of this input object type,
-otherwise an error should be thrown.
+otherwise a query error should be thrown.
 
 If any non-nullable fields defined by the input object do not have corresponding
 entries in the original value, were provided a variable for which a value was
-not provided, or for which the value {null} was provided, an error should
+not provided, or for which the value {null} was provided, a query error should
 be thrown.
 
 The result of coercion is an environment-specific unordered map defining slots
@@ -840,12 +840,12 @@ Original Value          | Variables       | Coerced Value
 ----------------------- | --------------- | -----------------------------------
 `{ a: "abc", b: 123 }`  | {null}          | `{ a: "abc", b: 123 }`
 `{ a: 123, b: "123" }`  | {null}          | `{ a: "123", b: 123 }`
-`{ a: "abc" }`          | {null}          | Error: Missing required field {b}
-`{ a: "abc", b: null }` | {null}          | Error: {b} must be non-null.
+`{ a: "abc" }`          | {null}          | Query error: Missing required field {b}
+`{ a: "abc", b: null }` | {null}          | Query error: {b} must be non-null.
 `{ a: null, b: 1 }`     | {null}          | `{ a: null, b: 1 }`
 `{ b: $var }`           | `{ var: 123 }`  | `{ b: 123 }`
-`{ b: $var }`           | `{}`            | Error: Missing required field {b}.
-`{ b: $var }`           | `{ var: null }` | Error: {b} must be non-null.
+`{ b: $var }`           | `{}`            | Query error: Missing required field {b}.
+`{ b: $var }`           | `{ var: null }` | Query error: {b} must be non-null.
 `{ a: $var, b: 1 }`     | `{ var: null }` | `{ a: null, b: 1 }`
 `{ a: $var, b: 1 }`     | `{}`            | `{ b: 1 }`
 

spec/Section 5 -- Validation.md

@@ -953,7 +953,7 @@ referenced.
 
 Named fragment spreads must refer to fragments defined
 within the document.  If the target of a spread is
-not defined, this is an error:
+not defined, this is a validation error:
 
 ```graphql counter-example
 {

spec/Section 6 -- Execution.md

@@ -698,5 +698,6 @@ resolves to {null}, then the entire list must resolve to {null}.
 If the `List` type is also wrapped in a `Non-Null`, the field error continues
 to propagate upwards.
 
-If all fields from the root of the request to the source of the error return
-`Non-Null` types, then the {"data"} entry in the response should be {null}.
+If all fields from the root of the request to the source of the field error
+return `Non-Null` types, then the {"data"} entry in the response should
+be {null}.

spec/Section 7 -- Response.md

@@ -6,7 +6,7 @@ operation if successful, and describes any errors encountered during the
 request.
 
 A response may contain both a partial response as well as encountered errors in
-the case that an error occurred on a field which was replaced with null.
+the case that a field error occurred on a field which was replaced with null.
 
 
 ## Serialization Format